In a three-dimensional memory of the following generations, a polycrystalline silicon (Si) thin film or a polycrystalline silicon germanium (SiGe) thin film is necessary, for example, for a channel of a bit cost scalable (BiCS) flash memory or the like. Those films are usually deposited as an amorphous Si thin film and an amorphous SiGe thin film so as to form the films in smooth morphology for excellently covering a step portion. Since the amorphous Si and SiGe thin films need to be finally changed into polycrystalline thin films to decrease the resistance, the amorphous thin films need to be crystallized by heat treatment.
In a case where the heat treatment is performed by conventional furnace annealing or lamp annealing, even if the temperature of the heat treatment is set to be high, there is caused a problem that grain diameters of a Si crystal and a SiGe crystal become small, so that the carrier mobility of a channel Si thin film and a channel SiGe thin film becomes low. In addition, since the temperature of the heat treatment is high, there is caused a problem of characteristic deterioration and the like in a peripheral transistor.
A known example of a method of forming the Si crystal having a large grain diameter by crystallizing the amorphous Si film is a method of forming the Si crystal by solid-phase growth using a Ge crystal in contact with the amorphous Si film as a nucleus. However, this method has problems that the process is complicated, the Ge nucleus is difficult to form, and it takes long time for the crystallization.